1. Field of the Invention
The present invention relates to an IP network and a communication method therein, and more particularly, to an IP network and a communication method therein for exchanging information on a common communication mode between terminals when a terminal communicating in an IP-based network such as a WLAN or Wibro supports several communication modes such as Voice over IP (VoIP) and Push to Talk (PTT).
2. Description of the Related Art
In recent years, various communication interfaces, such as wireless local area network (WLAN), wireless broadband Internet (Wibro), World Interoperability for Microwave Access (WiMax), and high-speed downlink packet access (HSDPA), are appearing, and various communication services using the various communication interfaces are being provided to users. One typical communication interface is code division multiple access (CDMA), generally used for voice communication service in Korea. Another is wireless local area network (WLAN), capable of high-speed Internet access through a personal digital assistant (PDA) or a notebook computer within a predetermined distance from a place where an access point (AP) is installed. Yet another is high-speed portable Internet WiBro (Wireless Broadband Internet), targeting not only ordinary data communication but also high-quality multimedia data communication based on quality of service (QoS), such as voice and video communication, using a frequency of 2.3 GHz. Still another is high-speed downlink packet access (HSDPA), a 3.5 generation version with an improved wireless Internet download speed, having an Internet transfer rate of a personal computer (PC), and mainly providing voice/video phone service and high-quality data service based on QoS.
The communication service provided through the communication interface may be VoIP (Voice over IP), VT (Video Telephony), PTT (Push To Talk), PTV (Push To Video), PTD (Push To Data), IM (Instant Messaging), or MMC (Multi Media Conference). VoIP is a communication mode in which a party is called using a dialer such as a general portable phone or using a buddy list, and voice packets are transmitted through an IP network. VT is a communication mode in which video data is communicated in addition to voice packets of VoIP.
PTT supports point-to-multi (group) communication in a packet network (wireless Internet), and is a signal that voice networks (circuit networks) and IP networks (packet networks) are moving into an age of “all IP networks”. In other words, PTT is the result of a trend of all wire/wireless network environments to be integrated with and developed into Internet protocol. PTT allows a member of one group having a terminal to communicate with other members of the same group, and is generally dependent on a single frequency, that is, on a dedicated channel. Since a dedicated channel is used, PTT is inevitably a half-duplex communication mode in which data can be transmitted in two ways, but not at the same time. In other words, when one party transmits data, the other party can only receive the data and cannot transmit data until reception is complete.
PTV is a technology in which live video can be transmitted in real time to several receivers at the same time. This technology provides a moving picture conference function, which however enables only one-way transmission. When a user desires, the one-way transmission can be to several recipients at the same time. Therefore, owing to its ability to provide the moving picture conference function at considerably low cost, PTV is regarded as a new key application in future third generation (3G) service. Like a messenger service widely used in PCs in recent years, in PTV, a user can manage a user group and be aware of a call recipient's reception or non-reception of transmitted data. Thus, not only can a plurality of contacts be designated and a moving picture conference be held, but a control function prevents conference participants from transmitting moving picture data at the same time. PTD provides a service enabling transmission of data to a plurality of recipients at the same time.
Push-to-all (PTA) supports PTT, PTV, and PTD services. In other words, PTA makes it possible to perform PTT, PTV, and PTD between one point and multiple other points. PTA can be applied in an asynchronous 2.5 generation (2.5G) edge terminal, a wide code division multiple access (WCDMA) terminal, a Wireless Fidelity (WiFi) terminal, and networks for these terminals. Meanwhile, IM refers to a computer application for instant text communication between two or more persons through a network such as the Internet, and MMC refers to a service allowing several users to concurrently communicate voice and video.
As communication modes become more diverse, user terminals become more diverse in kind, and terminals to which several communication modes are applied are beginning to appear. Even in a complex terminal to which several communication modes are applied, only a selected communication mode is used, and different communication modes are not compatible with each other. With new technology appearing daily, there is a substantial drawback in incorporating all communication modes into one complex terminal.
When a user attempts communication using a desired communication mode, not knowing whether the other party's terminal supports and is currently set up to use the communication mode, communication may not be possible due to communication mode incompatibility. Accordingly, what is needed is a communication system in which a call recipient's terminal is notified of possible communication modes of a caller's terminal and allows the recipient to select one of the communication modes.